Contacting device



Feb. 13, 1945.

FORCE DISPLACEMENT C. F. SPAHN, JR

CONTACTING DEVICE Filed July 9, 1941 INVENTOR c. ESPAHN, JR.

ATTORNEY Patented m. 13, 1945,

UNITED STATES PATENT OFFICE -z,so9,s1s I CONTACTING navrcr:

Charles F. Spahn, Jr New YorkfN. Y., assignor to Bell TelephoneLaboratories, Incorporated, New York, Y., a corporation of New YorkApplication July 9, 1941, Serial No. 401,593

2 Claims. (01. zooqer) This invention relates to contacting devices andparticularly to such devices employed in establishing electricalconnections.

The objects are to obtain an improved distribution of the operatingforces for contact springs, to secure a more reliable pressure betweenthe cooperating contacts, and to obtain other improvements in devices ofthis character.

Heretofore contact devices have been provided in which two or morecontact springs are arranged in a pile-up having contact surfaces orcontact points for establishing connections when these springs areactuated upon by an operator. These pile-.ups usually consist of flatflexible springs supported at one end and free formovement at theopposite ends.

A feature of the present invention is an arrangement of two or morecontact springs in a pile-up in which oneor more of these springs arecurved perpendicularly to their longitudinal axis so that when suchcurved springs are actuated upon to make contact with the other springs,an increasing pressure must be exerted, either mechanically or by anoperator, to bend these springs until the so-called break-through" orbreaking point is reached, at which time the pressure required to bendthese springs further to make the connections .desired decreases at arate faster than an operator is able to decrease the pressure. Thus, agood contact pressure is secured without the danger of failure in makingthe connection which may be the case where pressure is exerted to bendan ordinary flat spring.

It'is evident that the operating force for bending these curved springsmay be either manually or mechanically applied and it is another featureof the applicant's invention to arrange spring pile-ups containing oneor more such curved springs to be operated upon by a button controlledeither manually by an operator or mechanically by any other physicalforces as for example, by an armature of a relay whichwhen moved by theenergization of the relay exerts the desired pressure to operate thespring pile-up.

The invention is illustrated in the accompanying drawing, in which Fig.1 shows one embodiment of the applicant's invention; v

Fig. 2 shows a front view of thearrangement shown in Fig. 1;

Figs. 3 and 4 show a similar arrangement of another embodiment ofapplicant's invention;

Figs. 5 and 6 show an arrangement in which a button operates on a curvedspring; 4

Fig.7 shows a relay having an armature oper-- ating on curved springs inaccordance with the applicant's invention: while,

Fig. 8 shows curves of the operating forces required for the isplacementor a curved spring in accordance with the applicant's invention.

Referring now to the drawing, Fig. 1 shows an assembly comprising a longnarrow spring I curved transversely to have, for example, a semicircularcross section. On either side of this spring are two somewhat shortersprings 2 and 3 having rectangular cross sections. These three springsare assembled as shown at 4 by means of v intermediate insulation platesand bolts 0r screws to hold the springs together but insulated from eachother. As shown in Fig. 2, the curved spring I is heldby a concaveinsulation plate 5 on one side and a convex insulation plate 8 on theother side to maintain the curvature of this spring. Terminals as shownat I may extend from the assembly 4 for making the desired electricalconnections for these springs. In this case, the curved spring i may bemoved or bent by an operator in one direction or the other to makeconnection with the spring 2 or 3. Regardless of which direction springI is bent, it requires a certain amount of increasing pressure to moveit untilthe breaking point is passed when the pressure required forbendingthe spring I further to contact with spring 2 or 3 will beconsiderably less than the pressure required to make the spring reachthis breaking point. This required pressure to bend the spring furtherdecreases a great deal more rapidly than the operator is able to controlthe pressure exerted on the spring so that the operator will continue toact on spring I with a greater pressure than is required to bend itbeyond the breaking point, and in exerting this pressure the operatorcauses the spring I to contact with spring 2 or 3 with considerablecontact pressure to make a positive connection.

To illustrate the forces or pressures required for operating the springi, reference may be made to Fig. 8 in which the ordinate 8 indicatesforce expended and the abscissa 8 indicates displacements of the spring.The curve i8 indicates the varying pressure required for differentdisplace ments inregard to these two coordinate axes. For example, thedisplacement from rest to the breaking point Ii may be indicated by thedis- -.tance i2 and it will be noted by curve ill that a slow constantlyincreasing pressure is required for the bending of the springto thebreaking point Ii. If now the spring is bent further, for example, fromthe point I i to the point I3, it should be noted by the curve Iii thata rapidly decreasing pressure isrequired for the bending of the springto the point I3. If it is considered that when the I point is isreached, the spring i has been bent sufllciently to contact with thespring 2 or 8; it is evident that this rapid decrease in pressure required tov move the spring from 'i i to I3 is at a more rapid ratethanthe operator is able to control his rate of decrease in pressure on thespring which may be indicated by the dotted line curve H, Therefore,when the spring is bent to the point 13 it makes contact with one of thesprings 2 or 3 with a great deal more pressure exerted by the operatorthan was required to actually move the spring from point II to point l3and hence a good electrical connection is obtained. That is, the actualpressure exerted by the operator is or the value as at point I! whilethevalue of the pressure required to bend the spring to the contactingpoint I I is of the value as at the point It.

Figs. 3 and 4 show another arrangement of the applicants invention inwhich the curved spring I! is located between two other similarly curvedsprings l3 and I9 and these three springs are mounted as shown at 23 incurved insulation strips clamped together by screws. The purpose or thecurved. springs l3 and Iain this case is to enable the .use of somewhat.thinner spring :material lthansior the springs 2 or 3 and yet retainthe same rigidity of these springs by having them curved in the samemanner as spring ll, while the spring 11 will act in the same manner asspring I to secure a substantial contact pressure for establishingelectrical connections.

"In Figs. and 6 has been shown a somewhat diiierent arrangement in whichthe ilat spring 2| is mounted rigidly on two insulation studs 22 and 23on which are secured also a parallelly located supporting plate 24 bymeans of bolts 29 and 29 and associated nuts 21 and 28.- Between thespring 2| and plate 24 onstuds 22 and 23 a curved spring 29 is mounted.Stud 22 is provided with a decreased portion 39 on which spring 29 ismounted by having a hole cut in this spring 29 to fit over the portion39. The opposite end of the spring 29 may be provided with an oblonghole for the free movement longitudinally of the spring 29 on thedecreased portion 3| of stud 23. This permits the spring 29 to be bentdownwardly looking at Fig. 5. In the middle of the plate 24 is placed abutton 32 which engages with its enlarged lower surface the curvedspring 29 and the spring 29 and plate 2| are provided with normallyopened contacts 33. Ifpressure is exerted on the top of the button 32 topress it downwardly, it will act to bend the curved spring 29 downwardlyapproximately at its center to make spring 29 contact with plate 2|. Inthiscase, of course, as the spring 29 is prevented from longitudinalmovement by being secured on the stud 22, it will as it, is bent bybutton 32 shift-at its right-hand end on the stud 23, clearance for thismovement being provided by the oblong hole in the spring 29 at thisend.In this case, also, a

constantly increasing pressure is required to bend the spring 29 up tothe breaking point and after that connection is made between springs 29and plate 2| with considerable pressure-as the operator will not be ableto decrease the pressure on the button. 32 at the fast rateat which thepressure required fpr bending the. spring 2! beyond the breaking pointdecreases. It. is, of course, understood that the button 32. maybe-operated either manually byan operator putting his ringer on thebutton brby any mechanical means such as levers or cani's operated bysomeextemal' force.

.In Fig. '7 .is shown a relay 35. having a return pole-piece 39- andarmature 31' arranged so that when the. coil s5 is energizedthe armature31 will be drawn towards the core of this coil. Associated with thisarmature isa. pile-up of springs similar to thosedisclosed in. Figs..1to 4, except that in this case the pile-up consists of two curvedsprings 33 and 33 separated by an insulation stud 33 and two associatedflat stationary springs 32 and 33. The armature 31 engages normallythrough it's insulated end-piece 44 and 0 spring 33 so that when thearmature 31 is operated these two sprinss 33' and 33 will be movedtowards the left to engage respectively with the stationary springs 42and 43. These springs 33. 33, 42 and 33 may be mounted in any suitablei0 manner at a support 43 and connections may be 'extended from thesprings for establishing any desired electrical connections. In' thiscase when the armature 31 is attracted a certain amount a of force isrequired to move the springs 38 and 39 until the breaking point isreached. From this point on the required force is less but as thearmature continues to exert the same or intact J somewhat increasedpressure, due to the neamess of the armature to the magnet, a goodcontact 29 pressure will be secured between the curved and thestationary springs. It is evident that by arrangements, for example,asshown in Fig. '7, the inertia of the armature 31 may be suillcient tomove the springs 33 and 39 after the breaking point has been reachedeven though the energizing current through coil 35 may be discontinnedbefore the armature has actually completed its stroke. The operation ofthe armature under ordinary circumstances will provide a quick snapaction for closing the contacts after the breaking point has beenreached which, of course,

is desirable to prevent chattering of the contacts and sparking whichmay occur when uncertain connections are made to establish electricalconnections.

It should be understood thatthe curvature of the operating springs maybe varied to suit particular requirements and these springs may eitherbe prepressed before they are assembled with w other contact springs ona support or be pressed by clamping them between curved supportingplates while assembling with other contact springs without departingfrom thespirit of the invention. 45 What is claimed is:

1. A contact-making device comprising a long narrow spring curvedtransversely to its longitudinal axis, arigid support for said spring atone end thereof, a support at the other end of said spring permittingmovement of said spring only along its longitudinal axis, and fixedcontact members for establishing connections with said spring whenpressure is exerted on said spring between its supports to bend it.

2. Ina contact making device comprising a long, narrow spring; curvedtransversely to, its longitudinal axis, a, rigid contact plate below theconvexed surface of said spring, supporting means associated with saidplate for holding one end of said spring rigid to the plate and theother end movable longitudinally but rigid transversely, a

contact on said spring located centrally between its ends, a contact onsaid plate in position to connect with the 'contact on the spring, saidspring and plate and contacts thereof being so -iocated-that whenpressure is applied to said curvedspring in the center thereof to bendit towards the plate, the connection between the contacts'of the springand plate is not effected until the spring has been bent beyond itsbreak through point.

CHARLES F. SPAHN, JR.

